196 ELEMENTARY BIOLOGY. [CHAP. 



multi-articulate segment ; the former however is 

 but a fourth the length of the whole. 



8. Examine under a low power, and note that the 

 calcifications of the multi-articulate segments 

 are incomplete; they are restricted to their 

 outer borders. Both exopodite and endopodite 

 will be found to be fringed with delicate setae, -g 



The above description applies equally to both 

 Lobster and Crayfish, except that in the former 

 animal the whole appendage is more foliaceous 

 and paddle-like. 1 



0. The second 7naxillipede (second appendage in. 

 front of the great chela), as compared with a. ^ 



a. Its protopodite; its two segments are short and 

 equal in size. The distal one furnishes the base 

 of articulation for both exopodite and endopo- 

 dite; the proximal one is prolonged out into a 

 delicate lamella or epipodite (not represented in 

 a) which bears a well-defined gill. 



^. Its endopodite. This now forms the main por- 

 tion of the whole limb, it is subdivided into 

 five segments; a basal ischiopodite ; an elongated 

 laterally compressed 77ieropodiie ; a small carpo- 

 podite; an expanded propodite, and a short 

 terminal dactylopodite. The inner edge of the 

 dactylopodite is beset by a series of sharp 

 spines ; the rest of the endopodite is partly 

 fringed in setae. 



y. Its exopodite^ long and filamentous; its structu- 

 ral features recall most nearly those of the 

 endopodite of the abdominal appendage. 



